This research deals with the analysis of the gene for Acyl Carrier Protein (ACP), an essential protein cofactor for fatty acid synthesis. The organism understudy is Anabaena variabilis, an advanced nitrogen-fixing cyanobacterium. The objectives are: (1) to isolate and sequence the structural gene(s) for ACP from a gene library of A. variabilis, (2) to isolate and sequence from this same gene its promoter region, (3) to use the ACP structural gene as a probe to screen, isolate, and sequence the corresponding genes from the gene libraries of unrelated cyanobacteria, and (4) to compare the amino acid sequence of the cyanobacterial ACP with the published sequences of ACP's from spinach and E. coli. After the above objectives have been met, the following longer term objectives will be pursued: (1) if the genes for plant or E. coli ACP have not been isolated at that time, the A. variabilis ACP gene will be used as a probe to isolate those genes in order to determine the degree of homology between these genes as well as their respective promoters. (2) The regulation transcription of the ACP gene(s) will be analysed. (3) The gene of a second enzyme from fatty acid synthesis, malonyl-CoA-ACP transacylase, will be isolated and the relationship between this gene and the gene for ACP examined. The project is significant because currently the gene for this important protein cofactor has not as yet been isolated from any organism. Isolation of this gene will allow analysis of the promoter region and comparison of this promoter with promoters from other cyanobacteria and unrelated organisms. This analysis will contribute to the overall understanding of the important area of gene regulation. Determination of the degree of homology between genes of unrelated organisms contribute to our understanding of the evolution of organisms as well as metabolic pathways. In addition, as a nitrogen-fixing microorganism, cyanobacteria are a potential inexpensive food source. However, their fatty acid composition should be improved and knowledge of the molecular biology of this pathway would facilitate altering that composition. The overall approach will entail developing a DNA probe to isolate the ACP gene. The isolated gene would then be sequenced by the Sanger method and the regions upstream from the gene will be sequenced in order to locate the promoter. The isolated gene will then be used as a probe to isolate a family of ACP genes from unrelated cyanobacteria and organisms.